Perception of patterned vibratory stimulation: An evaluation of the tactile vision substitution system

Sensory substitution--The replacing of an impaired sensory channel by a properly functioning one--is possibly best manifested today in attempts to provide visual aids for the blind. The tactile vision substitution system (T.V.S.S.) is an example of one such visual aid. The system presents patterned tactile stimulation to the skin of the observer provided by the output of a closed-circuit television system. Research conducted with congenitally blind Ss in evaluation of the T.V.S.S. has provided useful information concerning the potentialities and limitations of the prototype systems, similarities and differences between tactile and visual perception, and the development of visual perception in the congenitally blind Investigation demonstrated that the congenitally blind Ss can learn to make valid judgements of three-dimensional displays with the T.V.S.S. Such judgements are made on the basis of properties contained in the proximal stimulation properties analogous to the monocular clues of depth presence in vision, such as linear-perspective, apparent elevation in the visual field, size change as a function of distance, occlusion, and texural gradients. Similarities have been noted between judgements made by sighted Ss using vision and by blind Ss using the T.V.S.S. on comparable tasks. A display consisting of two slightly displaced alternating lights is perceived in both situations as a single spot of light moving back-and-forth between two display boundaries. A rotating drum made up of alternate black and white stripes is, when stopped, perceived as briefly moving in the opposite direction. External localization of the source of stimulation also occurs with both sensory inputs. The major differences between the visual and tactile inputs that have been noted have occurred in form recognition tacks. Although blind Ss using the patterned tactile stimulation are able to identify both geometric forms and abstract patterns, accuracy is consistently lower than that of sighted Ss using vision, and the latencies for the blind Ss are significantly longer. It is hypothesized that the longer latencies for the blind Ss using the T.V.S.S. can be accounted for primarily by the need to hand-position the television camera during scanning. A major factor in the lower accuracy for the tactile group is the noted difficulty in detecting and identifying display features located within a mass of stimulation. This difficulty with internal display detail may be a function of sensory inhibition and/or masking. The research findings support a concept of sensory substitution as well as a theory of perception which stresses the modality of many qualities contained in visible displays. Further research is needed to determine the significance of sensor movement--either eye movements or camera manipulation--in the perceptual process

Dose-Reduced Busulfan, Cyclophosphamide, and Autologous Stem Cell Transplantation for Human Immunodeficiency Virus–Associated Lymphoma: AIDS Malignancy Consortium Study 020

AbstractIntensive chemotherapy for human immunodeficiency virus (HIV)-associated non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL) has resulted in durable remissions in a substantial proportion of patients. High-dose chemotherapy and autologous stem cell transplantation (AuSCT), moreover, has resulted in sustained complete remissions in selected patients with recurrent chemosensitive disease. Based on a favorable experience with dose-reduced high-dose busulfan, cyclophosphamide, and AuSCT for older patients with non-HIV–associated aggressive lymphomas, an AIDS Malignancy Consortium multicenter trial was undertaken using the same dose-reduced busulfan and cyclophosphamide preparative regimen with AuSCT for recurrent HIV-associated NHL and HL. Of the 27 patients in the study, 20 received an AuSCT. The median time to achievement of an absolute neutrophil count (ANC) of ≥ 0.5×109/L was 11 days (range, 9-16 days). The median time to achievement of an unsupported platelet count of ≥ 20×109/L was 13 days (range, 6-57 days). One patient died on day +33 posttransplantation from hepatic veno-occlusive disease (VOD) and multiorgan failure. No other fatal regimen-related toxicity occurred. Ten of 19 patients (53%) were in complete remission at the time of their day +100 post-AuSCT evaluation. Of the 20 patients, 10 were alive and event-free at a median of 23 weeks post-AuSCT. Median overall survival (OS) was not reached by 13 of the 20 patients alive at the time of last follow-up. This multi-institutional trial demonstrates that a regimen of dose-reduced high-dose busulfan, cyclophosphamide, and AuSCT is well tolerated and is associated with favorable disease-free survival (DFS) and OS probabilities for selected patients with HIV-associated NHL and HL

A GRFa2/Prop1/Stem (GPS) Cell Niche in the Pituitary

BACKGROUND: The adult endocrine pituitary is known to host several hormone-producing cells regulating major physiological processes during life. Some candidates to progenitor/stem cells have been proposed. However, not much is known about pituitary cell renewal throughout life and its homeostatic regulation during specific physiological changes, such as puberty or pregnancy, or in pathological conditions such as tumor development. PRINCIPAL FINDINGS: We have identified in rodents and humans a niche of non-endocrine cells characterized by the expression of GFRa2, a Ret co-receptor for Neurturin. These cells also express b-Catenin and E-cadherin in an oriented manner suggesting a planar polarity organization for the niche. In addition, cells in the niche uniquely express the pituitary-specific transcription factor Prop1, as well as known progenitor/stem markers such as Sox2, Sox9 and Oct4. Half of these GPS (GFRa2/Prop1/Stem) cells express S-100 whereas surrounding elongated cells in contact with GPS cells express Vimentin. GFRa2+-cells form non-endocrine spheroids in culture. These spheroids can be differentiated to hormone-producing cells or neurons outlining the neuroectoderm potential of these progenitors. In vivo, GPSs cells display slow proliferation after birth, retain BrdU label and show long telomeres in its nuclei, indicating progenitor/stem cell properties in vivo. SIGNIFICANCE: Our results suggest the presence in the adult pituitary of a specific niche of cells characterized by the expression of GFRa2, the pituitary-specific protein Prop1 and stem cell markers. These GPS cells are able to produce different hormone-producing and neuron-like cells and they may therefore contribute to postnatal pituitary homeostasis. Indeed, the relative abundance of GPS numbers is altered in Cdk4-deficient mice, a model of hypopituitarism induced by the lack of this cyclin-dependent kinase. Thus, GPS cells may display functional relevance in the physiological expansion of the pituitary gland throughout life as well as protection from pituitary disease

Advances in tissue engineering through stem cell-based co-culture

Stem cells are the future in tissue engineering and regeneration. In a co-culture, stem cells not only provide a target cell source with multipotent differentiation capacity, but can also act as assisting cells that promote tissue homeostasis, metabolism, growth and repair. Their incorporation into co-culture systems seems to be important in the creation of complex tissues or organs. In this review, critical aspects of stem cell use in co-culture systems are discussed. Direct and indirect co-culture methodologies used in tissue engineering are described, along with various characteristics of cellular interactions in these systems. Direct cell–cell contact, cell–extracellular matrix interaction and signalling via soluble factors are presented. The advantages of stem cell co-culture strategies and their applications in tissue engineering and regenerative medicine are portrayed through specific examples for several tissues, including orthopaedic soft tissues, bone, heart, vasculature, lung, kidney, liver and nerve. A concise review of the progress and the lessons learned are provided, with a focus on recent developments and their implications. It is hoped that knowledge developed from one tissue can be translated to other tissues. Finally, we address challenges in tissue engineering and regenerative medicine that can potentially be overcome via employing strategies for stem cel

Perception of patterned vibratory stimulation: An evaluation of the tactile vision substitution system

Sensory substitution--The replacing of an impaired sensory channel by a properly functioning one--is possibly best manifested today in attempts to provide visual aids for the blind. The tactile vision substitution system (T.V.S.S.) is an example of one such visual aid. The system presents patterned tactile stimulation to the skin of the observer provided by the output of a closed-circuit television system. Research conducted with congenitally blind Ss in evaluation of the T.V.S.S. has provided useful information concerning the potentialities and limitations of the prototype systems, similarities and differences between tactile and visual perception, and the development of visual perception in the congenitally blind Investigation demonstrated that the congenitally blind Ss can learn to make valid judgements of three-dimensional displays with the T.V.S.S. Such judgements are made on the basis of properties contained in the proximal stimulation properties analogous to the monocular clues of depth presence in vision, such as linear-perspective, apparent elevation in the visual field, size change as a function of distance, occlusion, and texural gradients. Similarities have been noted between judgements made by sighted Ss using vision and by blind Ss using the T.V.S.S. on comparable tasks. A display consisting of two slightly displaced alternating lights is perceived in both situations as a single spot of light moving back-and-forth between two display boundaries. A rotating drum made up of alternate black and white stripes is, when stopped, perceived as briefly moving in the opposite direction. External localization of the source of stimulation also occurs with both sensory inputs. The major differences between the visual and tactile inputs that have been noted have occurred in form recognition tacks. Although blind Ss using the patterned tactile stimulation are able to identify both geometric forms and abstract patterns, accuracy is consistently lower than that of sighted Ss using vision, and the latencies for the blind Ss are significantly longer. It is hypothesized that the longer latencies for the blind Ss using the T.V.S.S. can be accounted for primarily by the need to hand-position the television camera during scanning. A major factor in the lower accuracy for the tactile group is the noted difficulty in detecting and identifying display features located within a mass of stimulation. This difficulty with internal display detail may be a function of sensory inhibition and/or masking. The research findings support a concept of sensory substitution as well as a theory of perception which stresses the modality of many qualities contained in visible displays. Further research is needed to determine the significance of sensor movement--either eye movements or camera manipulation--in the perceptual process

Behavioral rigidity and manifest anxiety

The present research approaches the study of anxiety and behavioral rigidity through the use of two measuring instruments - the Taylor Manifest Anxiety Scale the (T.M.A.S.) and the Test of Behavioral Rigidity (the T.B.R.)

Blood-brain barrier promotes differentiation of human fetal neural precursor cells.

In the stem cell niche, neural stem cells (NSCs) are in close contact with the specialized blood-brain barrier (BBB) endothelial cells (ECs) that modulate their proliferation and differentiation behavior. NSCs are also an attractive source for cell transplantation and neural tissue repair after central nervous system injury. After systemic grafting, they are confronted with the BBB before they can enter the brain parenchyma. We investigated the interactions of human fetal neural precursor cells (hfNPCs) with human brain ECs in an in vitro model using primary cultures. We demonstrated that hfNPCs efficiently differentiate to neurons, astrocytes, and oligodendrocytes and move to the subendothelial space of human BBB endothelium, but not to pulmonary artery ECs. Effective differentiation was found to be dependent on the chemokine CCL2/MCP-1, but not on CXCL8/IL-8. Our findings suggest that neural precursor cells specifically interact with the BBB endothelium and differentiate in the subendothelial niche into astrocytes, neurons, and oligodendrocytes, under the influence of the chemokine CCL2/MCP-1.Journal ArticleResearch Support, Non-U.S. Gov'tFLWINinfo:eu-repo/semantics/publishe